KENNEDY SPACE CENTER, FLA. - In the Payload Hazardous Servicing Facility, workers prepare to mate the Mars Exploration Rover-2 (MER-2) to the third stage of a Delta II rocket for launch on June 5. NASA?s twin Mars Exploration Rovers are designed to study the history of water on Mars. These robotic geologists are equipped with a robotic arm, a drilling tool, three spectrometers, and four pairs of cameras that allow them to have a human-like, 3D view of the terrain. Each rover could travel as far as 100 meters in one day to act as Mars scientists' eyes and hands, exploring an environment where humans can?t yet go. MER-1 (MER-B) will launch June 25.